This application claims the priority of German application 198 58 303.6, filed on Dec. 17, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a forward structure for a self-supporting body shell of a passenger car, having two forward structure side members by means of which a function carrier is connected to at least four fastenings points in a force-transmitting manner, the function carrier being constructed of two cross member sections and two side member sections.
Such a forward structure is generally known for Mercedes-Benz passenger cars. The forward structure has two forward structure side members on whose underside an integral carrier serving as a function carrier is fastened by means of two fastening points respectively spaced with respect to one another in the longitudinal direction of the vehicle. The integral carrier carries a drive assembly as well as other vehicle function units. In the event of a frontal impact of a passenger car provided with such an integral carrier, a blocking may occur which reduces the energy absorbing capacity of the forward structure.
In order to avoid this, it is also known to design the two--viewed in the normal driving direction--rearward fastening points of the integral carrier such that they can be sheared off at the forward structure side members, and so that the integral carrier is separated at the fastening points from the forward structure in the event of a corresponding frontal impact and can therefore no longer cause a blocking.
It is an object of the invention to provide a forward structure of the initially mentioned type which, in comparison to the prior art, permits a further improved energy absorption in the event of a vehicle impact.
This object is achieved in that the function carrier is designed as a one-piece component which can be deformed at least in sections, in which case each side member section is provided with at least one geometrically caused desired deformation area which, in the event of a deformation of the forward structure side member in the longitudinal direction of the vehicle, can be plastically deformed. As a result, it is advantageously ensured that, in addition to the forward structure side members, the function carrier is also used for absorbing energy in the event of a corresponding vehicle impact. The function carrier can particularly be designed as a subframe or as an integral carrier and thus carry a chassis, a drive assembly and/or front axle parts. In this case, it is sufficient according to the invention if, during a corresponding forward structure deformation, the function carrier contributes to the supplementary energy absorption only along a portion of the deformation path and subsequently breaks since, because of the existing deformation on the function carrier, the occurred fracture is clearly the result of this deformation so that, with respect to product liability reasons, no difficulties will arise when the causes are examined. The energy absorbing capability, as a whole, which was increased by the additional energy absorption of the function carrier, in the area of an occupant compartment of the body shell, will result in a reduced leg space intrusion. In the side member area, the function carrier is preferably provided with a bend which is offset in a Z-shape and which represents the geometrically caused desired deformation area. The geometrically caused desired deformation area also forces a function carrier made of a non-ductile material under the influence of longitudinal force to carry out a deformation and therefore absorb energy.
In a further development of the invention, the component is produced as a cast component made of a metal material which has such a high ductility that, in the event of corresponding loads onto the forward structure, plastic deformations of the cast component in the desired deformation areas will occur before there is a breakage of the material. As mentioned above, this further development is advantageous for product liability reasons.
In a further development of the invention, as the desired deformation area, each side member section is provided with a bent area which is vertically offset in a Z-shape. This is a particularly advantageous further development for achieving targeted deformations of the function carrier. The deformability is the result of the geometrical design which causes a folding or upsetting of the side member sections in the event of corresponding deformations.
In a further development of the invention, the function carrier is screwed from the underside to the forward structure side members, the side member sections being positioned below the forward structure side members.
Additional advantages and characteristics of the invention are contained in the claims as well as in the following description of a preferred embodiment of the invention which is illustrated by means of the drawings.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.